In other games, Marseille thumped rock-bottom Montpellier 5-1 to reclaim second place by one point from Monaco, who drew 0-0 at home with fifth-placed Strasbourg.
PSG have already clinched the league title, and coach Luis Enrique rested 21-goal top-scorer Ousmane Dembélé and gave 17-year forward Ibrahim Mbaye a chance up front.
Another teenage forward, Désiré Doué, gave PSG an early lead with a deflected strike after being set up by winger Bradley Barcola's league-leading 10th assist.
The second goal came in the new half when 18-year-old midfielder Senny Mayulu broke down the left and allowed centre forward Gonçalo Ramos an easy tap-in.
Sloppy defending from a corner let striker Issa Soumaré head a goal back on the hour for Le Havre, who remained 16th and in the relegation playoff spot.
PSG are on course for the first treble in their history.
They travels to Arsenal on April 29 in the first leg of their Champions League semi-final, and take on Reims in the French Cup final on May 24.
The top three sides in France gain automatic entry into next season's Champions League while the side in fourth spot enters qualifying.
Marseille look well set with only four games left.
English forward Mason Greenwood scored twice against a woeful Montpellier to take his league tally to 18, with only Dembélé ahead of him.
Greenwood scored from the penalty spot eight minutes into a one-sided contest at Stade Velodrome.
Then defender Amir Murillo found Greenwood just inside the penalty area and he controlled the ball before finishing with a neat side-footed shot.
The visitors pulled a goal back before France midfielder Adrien Rabiot completed the scoring with a cool finish from Ismaël Bennacer's pass.
Montpellier are almost relegated after an 11th straight loss.
United States forward Folarin Balogun came off the bench late on for Monaco and almost scored when Dorde Petrovic tipped over his powerful header.
There was tension at the end between the two coaches.
Strasbourg's English coach Liam Rosenior claimed he had to wait five minutes before Monaco counterpart Adi Hütter shook his hand, which Hütter refuted.
"It's the first time in 16 years of my career that I have heard something like this," Hütter said. "I've coached in many countries, taken charge of 650 games. I've been in France for two years and a coach never said I disappointed them."
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